Chromatography Forum

I have an "injecting water onto the GCFID" question. We are taking our product and subjecting it to high amounts of water (50%-90%) to track the breakdown into its starting materials. I have read through other "water as solvent" posts on here and read about the volume expansion problem. Right now, the method we run to measure my analytes uses split 20:1. Is it not possible to measure my analytes by GCFID because of the water? Does anyone have an idea about the best way to go about this?

If I just dilute the sample in MeOH or ACN and then shoot it on, will that work or is that still going to be too much water? I have never used water as a solvent and I am just nervous about ruining something.

If anyone can help or point my in the right direction that would be great!

You should be fine. If you run a split and keep the oven starting temperature at 50C or higher there should be no issues with the water.

I agree, I think you're making too much about the water content. We assay alcohol products routinely on GC-FID capillaries, and they're all in water solutions and diluted with water. We inject 0.5ul.

Water is usually harmless to most GC phases and tubing. The exception to this rule if IF the water is in a liquid state and not as a vapor.

Always try to keep water in a gaseous state within the column and you should not have any problems. But liquid water, especially on certain PEG phases, should be avoided.

Best wishes,

Rodney George
consultant

Thank you for the responses.

I will inject some samples with varying concentrations of water to see what the peaks look like. I have set the injection volume to .2uL and the starting oven temp is 50C. I will post how it turns out.

SuperChemie,

HP, Agilent or Varian GC? I will be curious to hear about your results.

Best regards.